Sir Stelios Haji-Ioannou's latest outburst has served as a reminder, if one were needed, that easyJet is not your average FTSE 100 company.

In an open letter to shareholders published on Monday, the airline's founder and biggest shareholder hit out at what he described as its secret deal with Airbus to buy 135 planes, with options to buy a further 100.

Wielding his family's 37% stake, he warned fellow shareholders the board was trying to pull the wool over their eyes.

Stelios's objection is based on what he argues is the high risk inherent in buying too many aircraft too quickly and expanding into unprofitable routes.

This is despite the airline's assertion that 85 of the aircraft would replace ageing planes and that flexibility has been built into the deal to allow it to respond to economic conditions.

He also criticised the company's failure to disclose the discount it was getting on the aircraft, but at the same time was certain "that this is a good deal for Airbus and a bad deal for easyJet shareholders".

In January, he revealed that he had sold 200,000 shares in protest against the potential fleet expansion and his brother and sister sold the same number.

At the time he threatened to reduce his stake further should easyJet press ahead with the new plane orders. If shareholders do vote through the plans at the extraordinary meeting on 11 July, the board may be granted two wishes at once.

Stelios says he expects shareholders to approve the plans. But he is not out of the board's hair yet, and made clear his intention to keep up the pressure.

"I strongly believe public company directors should be legally held to account for their decisions. I will hold these directors to account, if at some point in the future it turns out that their decision to overcommit the company today was wrong."

Shareholders will be accustomed to their founder's outbursts, and in recent times they have been heartened by the company's record share price and rise to the dizzy heights of the FTSE 100 on the back of a business model that has been working.

Still, its elevated status has done nothing to change the fact it is at loggerheads with its founding father, and there is no sign that this will change any time soon.